Modelling of a residential solar stand-alone power system

Modelling of residential solar powered stand-alone power system comprising photovoltaic (PV) arrays, and a secondary battery is presented. Besides, an economic study is performed to determine the cost of electricity (COE) produced from this system so as to determine its competitiveness with the conventional sources of electricity. All of the calculations are performed using a computer code developed by using MATLAB^®. The code is designed so that any user can easily change the data concerning the location of the system or the working parameters of any of the system´s components to estimate the performance of a modified system. The system output was calculated for Cairo city (30°01´N, 31°14´E) in Egypt. It was found that maximum amount of hourly radiation on the photovoltaic arrays tilted by an angle of 30° facing south is 945.8 W/m² and is obtained in April. Also, the average maximum efficiency of the modelled 200 W solar cells was 12.098% with a maximum power of 162.172 W. The system which has an efficiency of 10.283% showed a great ability to satisfy the estimated demand load. The COE obtained from the system was found to be 44 cents/kWh over 20 years of its operation. This cost is high when compared with 30 cents/kWh for electricity produced using an off grid diesel generator and 6 cents/kWh for a similar grid connected house. However, an extra cost of 1.6 cents/kWh exists in case of considering removing CO₂ produced by the two conventional sources.